feat: support arbitrary values in helm install

[randmonkey]

support setting arbitrary values in installing kong by helm to support setting images.effectiveSemver to fix parsing semver in s integration tests against kong nightly image.
REVIEW: move the setting of other values to addon.addtionalValues?

[codecov-commenter]

Codecov Report

Patch coverage: 53.84% and project coverage change: -0.07% ⚠️

Comparison is base (045419a) 60.20% compared to head (caaf805) 60.14%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #776      +/-   ##
==========================================
- Coverage   60.20%   60.14%   -0.07%     
==========================================
  Files          48       48              
  Lines        3905     3914       +9     
==========================================
+ Hits         2351     2354       +3     
- Misses       1262     1267       +5     
- Partials      292      293       +1     

Flag	Coverage Δ
integration-test	60.14% <53.84%> (-0.07%)	⬇️

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Files Changed	Coverage Δ
pkg/clusters/addons/kong/addon.go	59.50% <0.00%> (-0.41%)	⬇️
pkg/clusters/addons/kong/builder.go	84.34% <70.00%> (-1.90%)	⬇️

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[rainest]

This could sorta screw with the additional env setting, but I don't think there's a need for guardrails. If you knowingly use both options to set env, woe be upon you.